diff --git a/lib/state/action-types.ts b/lib/state/action-types.ts
index c32960c35..3d6201842 100644
--- a/lib/state/action-types.ts
+++ b/lib/state/action-types.ts
@@ -1,3 +1,7 @@
+import * as T from '../types';
+
+import { AuthState } from './auth/constants';
+
 export const AUTH_SET = 'AUTH_SET';
 export const FILTER_NOTES = 'FILTER_NOTES';
 export const TAG_DRAWER_TOGGLE = 'TAG_DRAWER_TOGGLE';
@@ -7,7 +11,71 @@ export type Action<
   Args extends { [extraProps: string]: unknown } = {}
 > = { type: T } & Args;
 
-export type ActionType = never;
+/*
+ * Legacy action-creators that are more like global setters than Redux actions
+ */
+export type SetAccountName = Action<'setAccountName', { accountName: string }>;
+export type SetAutoHideMenuBar = Action<
+  'setAutoHideMenuBar',
+  { autoHideMenuBar: boolean }
+>;
+export type SetFocusMode = Action<
+  'setFocusMode',
+  { focusModeEnabled: boolean }
+>;
+export type SetFontSize = Action<'setFontSize', { fontSize?: number }>;
+export type SetLineLength = Action<
+  'setLineLength',
+  { lineLength: T.LineLength }
+>;
+export type SetMarkdownEnabled = Action<
+  'setMarkdownEnabled',
+  { markdownEnabled: boolean }
+>;
+export type SetNoteDisplay = Action<
+  'setNoteDisplay',
+  { noteDisplay: T.ListDisplayMode }
+>;
+export type SetSortReversed = Action<
+  'setSortReversed',
+  { sortReversed: boolean }
+>;
+export type SetSortTagsAlpha = Action<
+  'setSortTagsAlpha',
+  { sortTagsAlpha: boolean }
+>;
+export type SetSortType = Action<'setSortType', { sortType: T.SortType }>;
+export type SetSpellCheck = Action<
+  'setSpellCheck',
+  { spellCheckEnabled: boolean }
+>;
+export type SetTheme = Action<'setTheme', { theme: T.Theme }>;
+export type SetWPToken = Action<'setWPToken', { token: string }>;
+
+/*
+ * Normal action types
+ */
+export type FilterNotes = Action<'FILTER_NOTES', { notes: T.NoteEntity[] }>;
+export type SetAuth = Action<'AUTH_SET', { status: AuthState }>;
+export type ToggleTagDrawer = Action<'TAG_DRAWER_TOGGLE', { show: boolean }>;
+
+export type ActionType =
+  | FilterNotes
+  | SetAccountName
+  | SetAuth
+  | SetAutoHideMenuBar
+  | SetFocusMode
+  | SetFontSize
+  | SetLineLength
+  | SetMarkdownEnabled
+  | SetNoteDisplay
+  | SetSortReversed
+  | SetSortTagsAlpha
+  | SetSortType
+  | SetSpellCheck
+  | SetTheme
+  | SetWPToken
+  | ToggleTagDrawer;
 
 export type ActionCreator<A extends ActionType> = (...args: any[]) => A;
 export type Reducer<S> = (state: S | undefined, action: ActionType) => S;
diff --git a/lib/state/actions.ts b/lib/state/actions.ts
index da2aa708e..8eb2b0370 100644
--- a/lib/state/actions.ts
+++ b/lib/state/actions.ts
@@ -1,7 +1,9 @@
 import * as auth from './auth/actions';
 import * as settings from './settings/actions';
+import * as ui from './ui/actions';
 
 export default {
   auth,
   settings,
+  ui,
 };
diff --git a/lib/state/auth/actions.ts b/lib/state/auth/actions.ts
index bc3a9c813..ce360684f 100644
--- a/lib/state/auth/actions.ts
+++ b/lib/state/auth/actions.ts
@@ -1,34 +1,26 @@
-import { AUTH_SET } from '../action-types';
+import * as A from '../action-types';
 
-import {
-  Authorized,
-  Authorizing,
-  InvalidCredentials,
-  LoginError,
-  NotAuthorized,
-} from './constants';
-
-export const reset = () => ({
-  type: AUTH_SET,
-  status: NotAuthorized,
+export const reset: A.ActionCreator<A.SetAuth> = () => ({
+  type: 'AUTH_SET',
+  status: 'not-authorized',
 });
 
-export const setInvalidCredentials = () => ({
-  type: AUTH_SET,
-  status: InvalidCredentials,
+export const setInvalidCredentials: A.ActionCreator<A.SetAuth> = () => ({
+  type: 'AUTH_SET',
+  status: 'invalid-credentials',
 });
 
-export const setLoginError = () => ({
-  type: AUTH_SET,
-  status: LoginError,
+export const setLoginError: A.ActionCreator<A.SetAuth> = () => ({
+  type: 'AUTH_SET',
+  status: 'login-error',
 });
 
-export const setPending = () => ({
-  type: AUTH_SET,
-  status: Authorizing,
+export const setPending: A.ActionCreator<A.SetAuth> = () => ({
+  type: 'AUTH_SET',
+  status: 'authorizing',
 });
 
-export const setAuthorized = () => ({
-  type: AUTH_SET,
-  status: Authorized,
+export const setAuthorized: A.ActionCreator<A.SetAuth> = () => ({
+  type: 'AUTH_SET',
+  status: 'authorized',
 });
diff --git a/lib/state/auth/constants.ts b/lib/state/auth/constants.ts
index 74b4d100d..f70e7679f 100644
--- a/lib/state/auth/constants.ts
+++ b/lib/state/auth/constants.ts
@@ -1,5 +1,6 @@
-export const Authorized = Symbol();
-export const Authorizing = Symbol();
-export const InvalidCredentials = Symbol();
-export const LoginError = Symbol();
-export const NotAuthorized = Symbol();
+export type AuthState =
+  | 'authorized'
+  | 'authorizing'
+  | 'invalid-credentials'
+  | 'login-error'
+  | 'not-authorized';
diff --git a/lib/state/auth/reducer.ts b/lib/state/auth/reducer.ts
index 45d2f42b5..fb23a195e 100644
--- a/lib/state/auth/reducer.ts
+++ b/lib/state/auth/reducer.ts
@@ -1,11 +1,12 @@
 import { combineReducers } from 'redux';
 
-import { AUTH_SET } from '../action-types';
+import * as A from '../action-types';
+import { AuthState } from './constants';
 
-import { NotAuthorized } from './constants';
-
-export const authStatus = (state = NotAuthorized, { type, status }) =>
-  AUTH_SET === type ? status : state;
+export const authStatus: A.Reducer<AuthState> = (
+  state = 'not-authorized',
+  action
+) => ('AUTH_SET' === action.type ? action.status : state);
 
 export default combineReducers({
   authStatus,
diff --git a/lib/state/auth/selectors.ts b/lib/state/auth/selectors.ts
index dfffc82b3..e292f7096 100644
--- a/lib/state/auth/selectors.ts
+++ b/lib/state/auth/selectors.ts
@@ -1,20 +1,13 @@
-import { get } from 'lodash';
+import * as S from '../';
 
-import {
-  Authorized,
-  Authorizing,
-  InvalidCredentials,
-  LoginError,
-} from './constants';
+export const authIsPending = (state: S.State) =>
+  'authorizing' === state.auth.authStatus;
 
-export const authIsPending = state =>
-  Authorizing === get(state, 'auth.authStatus');
+export const hasInvalidCredentials = (state: S.State) =>
+  'invalid-credentials' === state.auth.authStatus;
 
-export const hasInvalidCredentials = state =>
-  InvalidCredentials === get(state, 'auth.authStatus');
+export const hasLoginError = (state: S.State) =>
+  'login-error' === state.auth.authStatus;
 
-export const hasLoginError = state =>
-  LoginError === get(state, 'auth.authStatus');
-
-export const isAuthorized = state =>
-  Authorized === get(state, 'auth.authStatus');
+export const isAuthorized = (state: S.State) =>
+  'authorized' === state.auth.authStatus;
diff --git a/lib/state/index.ts b/lib/state/index.ts
index c677213c6..eaabbfccf 100644
--- a/lib/state/index.ts
+++ b/lib/state/index.ts
@@ -4,7 +4,13 @@
  * All data should flow through here
  */
 
-import { compose, createStore, combineReducers, applyMiddleware } from 'redux';
+import {
+  Store as ReduxStore,
+  compose,
+  createStore,
+  combineReducers,
+  applyMiddleware,
+} from 'redux';
 import thunk from 'redux-thunk';
 import persistState from 'redux-localstorage';
 import { omit } from 'lodash';
@@ -73,6 +79,8 @@ export const store = createStore(
   )
 );
 
+export type Store = ReduxStore<State, A.ActionType>;
+
 export type MapState<StateProps, OwnProps = {}> = (
   state: State,
   ownProps: OwnProps
diff --git a/lib/state/settings/actions.ts b/lib/state/settings/actions.ts
index 509351157..042516330 100644
--- a/lib/state/settings/actions.ts
+++ b/lib/state/settings/actions.ts
@@ -1,8 +1,12 @@
 import { getIpcRenderer } from '../../utils/electron';
 
+import * as A from '../action-types';
+
 const ipc = getIpcRenderer();
 
-export const setFontSize = fontSize => ({
+export const setFontSize: A.ActionCreator<A.SetFontSize> = (
+  fontSize?: number
+) => ({
   type: 'setFontSize',
   fontSize,
 });
@@ -23,19 +27,20 @@ export const decreaseFontSize = () => (dispatch, getState) => {
   dispatch(setFontSize(fontSize - 1));
 };
 
-export const resetFontSize = () => setFontSize(undefined);
+export const resetFontSize: A.ActionCreator<A.SetFontSize> = () =>
+  setFontSize(undefined);
 
-export const activateTheme = theme => ({
+export const activateTheme: A.ActionCreator<A.SetTheme> = theme => ({
   type: 'setTheme',
   theme,
 });
 
-export const setNoteDisplay = noteDisplay => ({
+export const setNoteDisplay: A.ActionCreator<A.SetNoteDisplay> = noteDisplay => ({
   type: 'setNoteDisplay',
   noteDisplay,
 });
 
-export const setLineLength = lineLength => ({
+export const setLineLength: A.ActionCreator<A.SetLineLength> = lineLength => ({
   type: 'setLineLength',
   lineLength,
 });
@@ -47,7 +52,7 @@ export const toggleSortOrder = () => (dispatch, getState) => {
   });
 };
 
-export const setSortType = sortType => ({
+export const setSortType: A.ActionCreator<A.SetSortType> = sortType => ({
   type: 'setSortType',
   sortType,
 });
@@ -59,17 +64,17 @@ export const toggleSortTagsAlpha = () => (dispatch, getState) => {
   });
 };
 
-export const setMarkdown = markdownEnabled => ({
+export const setMarkdown: A.ActionCreator<A.SetMarkdownEnabled> = markdownEnabled => ({
   type: 'setMarkdownEnabled',
   markdownEnabled,
 });
 
-export const setAccountName = accountName => ({
+export const setAccountName: A.ActionCreator<A.SetAccountName> = accountName => ({
   type: 'setAccountName',
   accountName,
 });
 
-export const setWPToken = token => ({
+export const setWPToken: A.ActionCreator<A.SetWPToken> = token => ({
   type: 'setWPToken',
   token,
 });
diff --git a/lib/state/settings/reducer.ts b/lib/state/settings/reducer.ts
index 020282e9b..d101618fc 100644
--- a/lib/state/settings/reducer.ts
+++ b/lib/state/settings/reducer.ts
@@ -1,22 +1,28 @@
 import { clamp } from 'lodash';
 
+import * as A from '../action-types';
+import * as T from '../../types';
+
 export const initialState = {
-  accountName: null,
+  accountName: null as string | null,
   autoHideMenuBar: false,
   focusModeEnabled: false,
   fontSize: 16,
-  lineLength: 'narrow',
+  lineLength: 'narrow' as T.LineLength,
   markdownEnabled: false,
-  noteDisplay: 'comfy',
+  noteDisplay: 'comfy' as T.ListDisplayMode,
   sortReversed: false,
   sortTagsAlpha: false,
-  sortType: 'modificationDate',
+  sortType: 'modificationDate' as T.SortType,
   spellCheckEnabled: true,
-  theme: 'system',
-  wpToken: false,
+  theme: 'system' as T.Theme,
+  wpToken: false as string | boolean,
 };
 
-function reducer(state = initialState, action) {
+const reducer: A.Reducer<typeof initialState> = (
+  state = initialState,
+  action
+) => {
   switch (action.type) {
     case 'setAccountName':
       return { ...state, accountName: action.accountName };
@@ -50,6 +56,6 @@ function reducer(state = initialState, action) {
     default:
       return state;
   }
-}
+};
 
 export default reducer;
diff --git a/lib/state/ui/actions.ts b/lib/state/ui/actions.ts
index 946f46e05..d0c58dc12 100644
--- a/lib/state/ui/actions.ts
+++ b/lib/state/ui/actions.ts
@@ -1,13 +1,16 @@
-import { FILTER_NOTES, TAG_DRAWER_TOGGLE } from '../action-types';
-
+import * as A from '../action-types';
 import * as T from '../../types';
 
-export const filterNotes = (notes: T.NoteEntity[]) => ({
-  type: FILTER_NOTES,
+export const filterNotes: A.ActionCreator<A.FilterNotes> = (
+  notes: T.NoteEntity[]
+) => ({
+  type: 'FILTER_NOTES',
   notes,
 });
 
-export const toggleTagDrawer = (show: boolean) => ({
-  type: TAG_DRAWER_TOGGLE,
+export const toggleTagDrawer: A.ActionCreator<A.ToggleTagDrawer> = (
+  show: boolean
+) => ({
+  type: 'TAG_DRAWER_TOGGLE',
   show,
 });
diff --git a/lib/state/ui/middleware.ts b/lib/state/ui/middleware.ts
index b6fdee910..4cb1506c1 100644
--- a/lib/state/ui/middleware.ts
+++ b/lib/state/ui/middleware.ts
@@ -1,10 +1,12 @@
-import { AnyAction } from 'redux';
+import { AnyAction, Dispatch, Middleware } from 'redux';
 import { filterNotes as filterAction } from './actions';
 import filterNotes from '../../utils/filter-notes';
 
+import * as S from '../';
+
 let searchTimeout: NodeJS.Timeout;
 
-export default store => {
+export const middleware: Middleware<{}, S.State, Dispatch> = store => {
   const updateNotes = () =>
     store.dispatch(filterAction(filterNotes(store.getState().appState)));
 
@@ -43,3 +45,5 @@ export default store => {
     return result;
   };
 };
+
+export default middleware;
diff --git a/lib/state/ui/reducer.ts b/lib/state/ui/reducer.ts
index 14592a846..5b780de2a 100644
--- a/lib/state/ui/reducer.ts
+++ b/lib/state/ui/reducer.ts
@@ -1,20 +1,23 @@
 import { difference, union } from 'lodash';
 import { combineReducers } from 'redux';
-import { FILTER_NOTES, TAG_DRAWER_TOGGLE } from '../action-types';
 
+import * as A from '../action-types';
 import * as T from '../../types';
 
 const defaultVisiblePanes = ['editor', 'noteList'];
 const emptyList: unknown[] = [];
 
-const filteredNotes = (
+const filteredNotes: A.Reducer<T.NoteEntity[]> = (
   state = emptyList as T.NoteEntity[],
-  { type, notes }: { type: string; notes: T.NoteEntity[] }
-) => (FILTER_NOTES === type ? notes : state);
+  action
+) => ('FILTER_NOTES' === action.type ? action.notes : state);
 
-const visiblePanes = (state = defaultVisiblePanes, { type, show }) => {
-  if (TAG_DRAWER_TOGGLE === type) {
-    return show
+const visiblePanes: A.Reducer<string[]> = (
+  state = defaultVisiblePanes,
+  action
+) => {
+  if ('TAG_DRAWER_TOGGLE' === action.type) {
+    return action.show
       ? union(state, ['tagDrawer'])
       : difference(state, ['tagDrawer']);
   }
diff --git a/lib/types.ts b/lib/types.ts
index b1f507607..b6bc68ac8 100644
--- a/lib/types.ts
+++ b/lib/types.ts
@@ -63,4 +63,8 @@ export type Bucket<T> = {
 ///////////////////////////////////////
 
 export type EditorMode = 'edit' | 'markdown' | 'preview';
+export type LineLength = 'full' | 'narrow';
+export type ListDisplayMode = 'expanded' | 'comfy' | 'condensed';
+export type SortType = 'alphabetical' | 'creationDate' | 'modificationDate';
+export type Theme = 'system' | 'light' | 'dark';
 export type TranslatableString = string;